Illuminated indicating instrument with replaceable lamps



1979 D. J. BLACKWELL 5 ILLUMINATED INDICATING INSTRUMENT WITH REPLACEABLE LAMPS Filed March 26, 1968 2 Sheets-Sheet 1 I NVENTOR.

Dana J Blackwell 3,526,762 ILLUMINATED INDICATING INSTRUMENT WITH REPLACEABLE LAMPS Dana J. Blackwell, Naugatuck, Conn., assignor to Lewis Engineering Company, Naugatuck, Conn., a corporation of Connecticut Filed Mar. 26, 1968, Ser. No. 716,189 Int. Cl. B60q 3/04 U.S. Cl. 240-21 6 Claims ABSTRACT OF THE DISCLOSURE An indicating instrument having on its casing a bezel surrounding the front window and having illuminating lamps in the casing. The bezel has one or several small removable screws or plugs which, when removed, result in the illuminating lamps being shifted and made readily accessible for replacement without requiring dismantling of the instrument casing.

Prior patents of interest U.S. Pat. No. 2,874,671, Blackwell et al., Feb. 24, 1959 U.S. Pat. No. 3,029,334, Anderson et al., Apr. 10, 1962 U.S. Pat. No. 3,143,098, Blackwell, Aug. 4, 1964 BACKGROUND SUMMARY The above drawbacks and disadvantages of prior illuminated instruments are obviated by the present invention, and one object of the invention is to provide an improved illuminated indicating instrument employing miniature incandescent electric lamps, wherein easy and quick removal and replacement of the lamps without dismounting or dismantling the casing is possible while at the same time full and complete reliability of the electrical lighting circuit is maintained at all times. This is accomplished by utilizing miniature lamp and socket assembles adjacent the front of the meter or instrument, with permanent leads on the sockets whereby electrical reliability is maintained, and by providing a simple and effective mechanical system to enable shifting of the lamp or lamps to be had for replacement purposes, through suitable openings in the instrument bezel at the face of the instrument. The bezel openings are normally covered by removable closures or plugs which, when taken off, result in the lamps being shifted forward to effect their removal from the sockets. The removable plugs may advantageously be constituted as small screws, preferably provided with depressions to nest the forward portions of the lamps.

Other features of the invention reside in an improved illuminated indicating instrument as above, which is espe cially efficient and effective, simple in construction, relatively inexpensive to produce, easily assembled, and rugged so as to withstand vibration and other adverse conditions of use.

Other features and advantages will hereinafter appear.

United States Patent In the drawings:

FIG. 1 is a front elevational view of an illuminated indicating instrument or meter as provided by the invention.

FIG. 2 is a fragmentary top plan view of the instrument, showing the front portion thereof with the casing and instrument movement removed.

FIG. 3 is a fragmentary vertical sectional view, taken on the line 33 of FIG. 2.

FIG. 4 is a fragmentary axial sectional view, greatly enlarged, taken on the line 4-4 of FIG. 1.

FIG. 5 is a view partly in side elevation and partly in axial section, of a lamp holder device employed in the instrument.

FIG. 6 is a rear elevational view of the lamp holder device of FIG. 5.

As shown, the instrument comprises a casing 10 (shown partially in broken outline in FIG. 2) carrying at its front a face plate or annular bezel 12 in which there is mounted a window 14 of the kind adapted to be edge lighted. The window 14 may be of any usual construction involving prisms or wedges 16, 18 as is well understood in the art.

The instrument has a dial, including a scale or indicia 20 and one or more pointers 22, as is common practice.

In accordance with the present invention a novel and improved lighting means or assembly is provided for effecting illumination of the instrument dial, indicia 20 and pointer 22, such lighting means comprising miniature incandescent lamps and sockets therefor, so arranged that the lamps may be easily and quickly replaced from the front of the instrument without requiring dismounting, or dismantling of the casing 10 thereof.

As shown, the illumination means comprises a pair of identical lighting units 24, 26 only one of which, for the sake of brevity, will be described in detail. The lighting unit 26 comprises a lamp holder in the form of a tube 28 disposed within the casing at the rear of the bezel 12, said tube having a pair of angle brackets 30 which are secured to the rear of bezel by suitable screws 32. The angle brackets 30 may be spot welded to the exterior of the holder tube 28, as indicated.

Referring to FIGS. 4 and 5, the forward edge of the holder tube 28 has a notch 34 which adjoins the edge portion of the window 14 as clearly shown in FIG. 4, for the purpose of enabling light from the lamp to strike such edge portion, as explained below. The inner wall of the holder tube 28 comprises a guide means which extends in forward and rearward directions, and within the tube there is a lamp socket comprising portions 36, 38 which are movable as a unit forwardly and rearwardly of the holder. The portion 36 is of larger diameter and slidably fitted in the holder tube 28, being spring-urged forwardly by a compression coil spring 40 engaging the back surface of said portion. The coil spring 40 also engages an annular abutment 42 at its back end, said abutment being aflixed in the holder tube 28 at the rear portion thereof as by spot welding.

The lamp socket 36, 38 has terminals 44, 46 to which are connected respectively lead wires 48, 50, said terminals and wires being disposed within the coil spring 40, and the wires extending rearward through the annular abutment 42 as shown in FIG. 4.

To provide effective insulation around the terminals 44, 46 at the connections to the lead wires 48, 50, a plastic insulating sleeve 51 is provided, having a heat shrink characteristic whereby it can be shrunk in place to prevent its displacement.

Mounted in the socket 36, 38 is a miniature incandescent lamp 52 of the type often referred to as a grain of wheat, such lamp having terminal pins 54 projecting 3 from its base portion 56 and adapted to be received in cooperable spring sleeves (not shown) of the socket 36, 38. The lamp 52 has a glass envelope 58 which is accommodated in a stepped opening 60, 62 provided in the bezel 12, such opening being sufficiently large in diameter to easily pass the lamp 52.

A cover piece 64 is provided for the bezel opening 60, 62, such cover piece being engageable with the front end of the lamp 52 to hold the latter in the socket 36, 38 and thereby to maintain the socket in its retracted position as illustrated in FIG. 4 against the action of the biasing spring 40. The cover piece 64 is adapted to be releasably fastened to the bezel, and for this purpose the cover piece may be advantageously constituted as a screw, having threads engaging a threaded portion of the opening 62 of the bezel as shown.

For the purpose of holding captive the cover screws 64, these are carried in apertured end portions of flexible straps 65 which are secured by screws 67 to the front of the bezel 12. Accordingly, when the screws 64 are removed, there is no likelihood or possibility of their dropping or becoming lost.

The cover piece or screw 64 has, in accordance with the invention, a plastic facing 66 constituted of heat resistant, heat-insulating material such as Teflon. .As seen in FIG. 4, the facing 66 is in the form of a plug, having at its exposed end a concavity or socket 68 adapted to nest the foremost portion of the lamp envelope 58. The screw 64 is recessed to receive the plastic plug 66, and preferably has an annular undercut 70 to interlock with an annular shoulder 72 on the plug. Assemblage of the plug 66 to the screw 64 is effected by a press operation utilizing a punch, whereby the Teflon material is temporarily deformed to overcome the interference represented by the annular shoulder 72. After assemblage, the plug 66 resumes its original shape, wherein the shoulder 72 again expands and occupies the annular undercut 70 of the screw.

It will be noted that the filament 53 of the lamp 52 is directly adjacent the notch 34 of the holder tube 28, whereby light from the filament can pass directly to and strike the edges of the prisms 16, 18 to effect the desired illumination of the instrument indicia.

Operation of the lighting device illustrated in FIG. 4, for the purpose of removing and replacing the lamp 52 is especially simple. The cover screw 64 is merely removed, as by using a thin coin in the slotted head. As the screw leaves the opening 60, 62 of the bezel, the coil spring 40 will advance to the right the lamp 52 and the socket 36, 38. The small-diameter portion 38 the socket can now occupy the small diameter bore of the bezel opening, and the large diameter portion of the socket will occupy the large diameter portion 60 of the bezel opening. The annular shoulder or ledge 74 of the socket will engage and be stopped by the corresponding shoulder 76 in the bezel. The shoulders 74 and 76 constitute a stop means. The lamp 52 will now be fully exposed and accessible, and may be removed by simply pulling it forward, out of the socket 36, 38. A new lamp can then be easily inserted, by fitting the prongs 54 thereof into the cooperable spring sleeves of the socket 36, 38 whereupon the screw 64 is applied to the front portion of the lamp to force the latter and the socket to their retracted positions illustrated in FIG. 4. The lamp and socket are maintained in these positions by fastening the screw in the usual manner.

It will now be seen from the foregoing that I have provided a novel and improved indicating meter and illuminating system therefor, whereby removal and replacement of the incandescent lamps may be easily and quickly effected without requiring dismounting of. the instrument or dismantling of the casing thereof. The entire replacement procedure is effected from the front of the instrument, and is quickly carried out without special tools or skills. The removable cover pieces or screws are held captive, and accordingly cannot be dropped or lost to defeat the replacement procedure. The construction is relatively simple, inexpensive, easily assembled, and especially effective and reliable in operation, with no possibility of failure of the lighting circuit. This latter is accomplished by elimination of all contact brushes, fingers or other contacting means capable of failure due to vibration and the like. The circuit through th lamp from the lead waires 48, is always fully maintained due to the straight-forward direct socket mounting for the lamp.

Variations and modifications are possible, and portions of the improvement may be used without others.

I claim:

1. An indicating instrument having an enclosing casing and a lighting assemblage comprising, in combination:

(a) an annular bezel at the front of the instrument casing,

(b) a transparent window carried by said bezel and adapted to be edge lighted,

(c) a lamp holder disposed within the casing at the rear of the bezel,

(d) a lamp socket in said holder, said socket comprising an insulating body adapted to receive contacts on a lamp base,

(e) a lamp carried in said socket and extending forwardly thereof,

(f) said bezel having an opening providing access to the socket and adapted to pass a lamp therethrough for insertion into the socket,

(g) a cover piece for said bezel opening,

(h) means for releasably fastening the cover piece to the bezel, over the said opening thereof,

(i) the said lamp holder having forward and rearward extending guide means,

(j) said lamp socket being movable forwardly and rearwardly in the guide means of the holder,

(k) means engaged with said insulating body, biasing the socket forwardly,

(1) said cover piece maintaining the lamp in the socket and thereby the socket in a retracted position against the action of said biasing means,

(m) said lamp holder comprising a holder tube adapted to receive the lamp and lamp socket,

(n) said tube having an opening in its wall to enable light from the lamp to pass out of the tube,

(0) said guide means of the lamp holder comprising the inner walls thereof,

(p) said lamp socket slidably fitting the inner walls of the lamp holder,

(q) said biasing means comprising a spring engaged with the back end of the socket,

(r) an annular abutment secured in the back end of said holder tube and engaged with the back end of the spring,

(s) and lead wires connected with the contacts of the socket and passing from said socket through said spring and abutment, and out through the back end of the holder tube, said socket when shifted forward in the lamp holder by said biasing means having its forward portions accessible in the opening of the bezel.

2. The invention as defined in claim 1, and further including:

(a) a stop located at the front end of the holder tube, engageable with the insulating body of the socket, for preventing complete withdrawal of the socket forwardly of the holder tube,

(b) said cover piece comprising a screw threaded into the bezel, having a socket-shaped means for engagement with the front end of said lamp.

3. The invention as defined in claim 1, wherein:

(a) the cover piece is of metal and includes a heatinsulating and heat-resistant plastic facing for engage ment with the front end of the lamp,

(b) said cover piece and facing constituting a socket.

4. The invention as defined in claim 2, wherein:

(a) the socket-shaped means of the screw comprises a plastic plug having interlocking engagement with the screw,

(b) said screw having an undercut recess in which the plug is disposed,

(c) said plug having an annular shoulder interlocked in said recess.

5. An indicating instrument having an enclosing casing and a lighting assemblage comprising, in combination:

(a) a face plate at the front of the instrument casing adjacent a transparent window which is adapted for edge lighting,

(b) an elongate hollow lamp holder disposed Within and extending forward and rearward in the casing at the rear of the face plate,

(c) a lamp socket disposed in said holder, said socket comprising an insulating body adapted to receive contacts on a lamp base,

(d) a lamp carried in said socket, extending forwardly therefrom,

(e) said face plate having an opening to provide access to the socket and to pass a lamp therethrough for insertion into the socket,

(f) a removable cover piece for covering said face plate opening,

(g) said socket being forwardly and rearwardly movable in the lamp holder,

(b) means biasing the socket forwardly in the lamp holder, said cover piece being engageable with the NORTON ANSHER,

R. L. MOSES, Assistant Examiner lamp and maintaining the latter and socket in a rearward position in the holder against the action of said biasing means,

(i) stop means including a stop shoulder on the insnlating *body of the socket, preventing complete withdrawal of the latter forwardly of the lamp holder,

(j) said stop means enabling forward portions of the socket to be accessible in the face plate opening.

6. An instrument as in claim 5, wherein:

(a) the insulating body of the socket comprises a large diameter rear portion,

(b) said forward portions of the body being of smaller diameter than said rear portion,

(c) said stop shoulder comprising an annular ledge between said rear portion and said forward portions.

References Cited UNITED STATES PATENTS 2,413,381 12/1946 Rylsky 2402.1 2,677,045 4/1954 MacArthur 240-816 2,827,557 3/1958 Neugass 2402.1 2,837,628 6/1958 Lamb et al. 2402.1 2,875,320 2/1959 Campbell 2402.1 3,320,412 5/1967 Howland 240-2.1

Primary Examiner US. Cl. X.R, 

